Pre-biotic molecules in Martian dust clouds

Abstract

THE search for life on Mars has so far proved disappointing¹. Experiments on the Viking package were designed on the presumption that any microbial life on Mars would be endowed with metabolic processes similar to present-day microorganisms on Earth. Analyses of gases released in soil heating experiments² have provided no evidence for significant abundances of highly complex organic molecules. These data are however, limited to only two landing sites and moreover the compositional studies carried out so far reflect properties of only a relatively thin dust layer on the Martian surface. Dust sucked up into the atmosphere from large areas of the planet's surface would have been witnessed in the 1971 storm, representing a much broader sampling of Martian surface material. Here we propose that a broad absorption feature centred on a wavelength close to 2,200 Å, derived from scattering studies of these dust clouds, may be a signature of highly complex organic or prebiotic molecules.